In an optical communication system, it is generally necessary to couple an optical fiber to an optical communications device (i.e., an optical transmitter, receiver or transceiver device), and to, in turn, couple the device to an electronic system such as a switching system or processing system. These connections can be facilitated by modularizing the optical communications device. Such modules include a housing in which are mounted opto-electronic elements, optical elements, and electronic elements, such as one or more light sources (e.g., lasers), light sensors (e.g., photodiodes), lenses and other optics, digital signal driver and receiver circuits, etc. In addition, an optical communications module typically includes an optical connector that can be coupled to a mating connector at the end of a fiber-optic cable. Various optical communications module configurations are known.
In switching systems that are commonly used in optical communications networks, each optical transceiver module is typically mounted on a circuit board that is interconnected with another circuit board that is part of a backplane of the switching system. The backplane typically includes many circuit boards that are electrically interconnected with one another. In many such switching systems, each circuit board of the backplane has at least one application specific integrated circuit (ASIC) mounted on it and electrically connected to it. Each ASIC is electrically interconnected with a respective optical transceiver module via electrically-conductive traces of the respective circuit boards. In the transmit direction, each ASIC communicates electrical data signals to its respective optical transceiver module, which then converts the electrical data signals into respective optical data signals for transmission over the optical fibers that are connected to the optical transceiver module.
In the receive direction, the optical transceiver module receives optical data signals coupled into the module from respective optical fibers and converts the respective optical data signals into respective electrical data signals. The electrical data signals are then output from the module and are received at respective inputs of the ASIC, which then processes the electrical data signals. The electrical interconnections on the circuit boards connect inputs and outputs of each ASIC to outputs and inputs, respectively, of each respective optical transceiver module. These electrical interconnections are typically referred to as lanes.
FIG. 1 illustrates a block diagram of a known optical communications system 2 of a known switching system. The optical communications system 2 comprises a first circuit board 3, an optical transceiver module 4 mounted on the first circuit board 3, a backplane circuit board 5, and an ASIC 6 mounted on the backplane circuit board 5. Four output optical fibers 7 and four input optical fibers 8 are connected to the optical transceiver module 4. In the transmit direction, the ASIC 6 produces four 10 gigabit per second (Gpbs) electrical data signals, which are output from the ASIC 6 onto four respective output lanes 9 to the optical transceiver module 4. The optical transceiver module 4 then converts the four 10 Gbps electrical data signals into four respective 10 Gbps optical data signals and couples them into the ends of four respective optical fibers 7 for transmission over the optical fiber link.
In the receive direction, four 10 Gbps optical data signals are coupled from the ends of four respective optical fibers 8 into the optical transceiver module 4, which then converts the optical data signals into four 10 Gbps electrical data signals. The four 10 Gbps electrical data signals are then output over four respective input lanes 11 to four respective inputs of the ASIC 6 for processing by the ASIC 6. Thus, the optical fiber link has a data rate of 40 Gbps in the transmit direction and 40 Gbps in the receive direction. The data rate of the optical fiber link can be increased by increasing the number of optical transceiver modules 4 and ASICs 6 that are included in the link. For example, if four optical transceiver modules 4 and four ASICs 6 are included in the optical communications system 2, the optical fiber link will have a data rate of 160 Gbps in the transmit direction and 160 Gbps in the receive direction.
Demands for greater bandwidth often lead to efforts to upgrade optical communications networks to achieve higher data rates. Doing so, however, typically requires either duplicating the number of optical transceiver modules and ASICs that are used in the optical communications system or replacing them with optical transceivers and ASICs that operate at higher data rates. Of course, duplicating the number of optical transceiver modules and ASICs that are used in the optical communications system is a very costly solution. Replacing the ASICs with ASICs that operate at higher data rates requires redesigning the ASIC, which also is a very costly solution. It would be desirable to provide a way to substantially increase the bandwidth of an optical fiber link of an optical communications network without having to duplicate the number of optical transceiver modules and ASICs that are employed and without having to redesign the ASIC.